How do I work with all this data without making my URLs too long?

[eluser]eilrahc[/eluser]
http://example.com/controller/function/c...t_by_date/

I don't see anything particularly wrong with this, actually. As long as you've thought it through and the organization makes sense, there shouldn't be a good reason not to do this unless you're delibeately planning to change it in the future. If it comes up that it *must* be changed, there are numerous ways to redirect to the new content (mod_rewrite, CI routing, or redirecting within the URL itself). Or you could use a redirection technique right in the beginning, by using links like:

http://example.com/searchcity/12345